Cutting inserts for material machining, in particular for cutting metal machining, comprise a substrate body of carbide, cermet, ceramic, steel or high speed steel which in most cases is provided with a single-layer or multi-layer carbide coating for improving the cutting and/or wearing properties. The carbide coating comprises mutually superposed layers of monometallic or mixed-metallic carbide phases. Examples of monometallic carbide phases are TiN, TiC, TiCN and Al2O3. Examples of mixed-metallic phases in which in a crystal one metal is partially replaced by another are TiAlN and TiAlCN. Coatings of the above-indicated kind are applied by CVD processes (chemical vapour phase deposit), PCVD processes (plasma-assisted CVD processes) or PVD processes (physical vapour phase deposit).
It has been found that certain preferential orientations of crystal growth in the deposit in the PVD or CVD process can have particular advantages, in which respect different preferential orientations of given layers of a coating can also be particularly advantageous for different uses of the cutting insert. The preferential orientation of growth is generally specified in relation to the plane of the crystal lattice, defined by way of the Miller index and is referred to as the crystallographic texture (for example fibre texture).
DE 10 2005 032 860 discloses a carbide coating with a layer of cubically face-centred T1-xAlxCyNz with an Al content of 0.75≤z<0.93 and a process for the production thereof.
DE 10 2007 000 512 discloses a carbide coating with a layer of TiAlN which is deposited on a first layer of TiN, TiCN or TiC deposited directly on the substrate, and a bonding layer provided between the two layers, with a phase gradient. The layer of TiAlN has a preferential orientation of crystal growth with respect to the (200) plane of the crystal lattice.
Laid-open specifications WO 2009/112115, WO 2009/112116 and WO 2009/112117A1 disclose TiAlN and TiAlCN layers deposited by means of CVD processes with a high Al proportion and a cubically face-centred lattice, but no crystallographic preferential orientations of crystal growth are described.
TiAlN coatings produced by means of PVD processes, with various crystallographic preferential orientations of crystal growth, are known, but PVD coatings with cubically face-centred lattices of the TiAlN coatings, in contrast to CVD coatings are restricted to Al contents of less than 67%. TiAlN coatings with a crystallographic preferential orientation of the {200} plane with respect to the growth direction of the crystallites are described as advantageous for metal machining (for example US 2009/0274899, US 2009/0074521 and WO 2009/127344).